The long-term behavior of GaAlAs

-groove lasers has been investigated with respect to the lifetime and to the changes in optical properties that are relevant to the operation of these lasers in an optical communication system. For lasers from two wafers, median lifetimes of 8800 and 11 000 h were obtained at an operation temperature of 70°C. With activation energies of 0.7 and 0.95 eV, median lifetimes between

and

h for room temperature can be extrapolated. The corresponding standard deviations are 1.7 and 0.9, respectively. During the operation of more than 10000 h at

, the emission characteristic, the optical spectrum, and the dc signal/noise ratio show only nonessential changes. It should be emphasized that no self-pulsations can be observed even after this long operation time.